In a compressor, which compresses refrigerant gas, it is known to place an increased volume portion, which serves as a silencer, in a passage located immediately after a discharge valve in order to reduce pulsation of the refrigerant gas. Furthermore, in a case where a frequency of a sound, which needs to be lowered, is obvious due to presence of a resonance frequency of, for example, a valve of a compressor, or a resonance frequency of a vibration of a conduit of a refrigerant cycle or a heat exchanger, it is known to use a Helmholtz resonator, which can provide a pulsation damping effect for the frequency of the sound, which needs to be lowered.
The compressor, which uses the Helmholtz resonator, is recited in the Patent Literatures 1, 2. The Patent Literature 1 discloses a technique of placing the Helmholtz resonator immediately after a location where compression of the refrigerant takes place in a vane compressor. In the compressor of the Patent Literature 1, an oil separator is placed on a downstream side of a discharge passage located on a downstream side of a discharge chamber that is used as a silencer chamber of the Helmholtz resonator.
The Patent Literature 2 discloses a technique of placing a resonance chamber of a Helmholtz resonator at a location, which is closed by a valve plate and an intake valve at a discharge port that discharges refrigerant in a compressor having multiple pistons received in multiple cylinders. Therefore, the resonance chamber of the Helmholtz resonator is placed on an upstream side of a discharge valve and a discharge chamber.
In the apparatuses disclosed in the Patent Literatures 1, 2, the resonator is placed in a location where a sufficient amount of lubricating oil is contained. Therefore, when the lubricating oil flows into a choking passage of the resonator (a narrow passage communicated with the resonance chamber), there may occur phenomenon of, for example, that a passage cross-sectional area of the choking passage is reduced by the lubricating oil, or the lubricating oil is trapped in the resonance chamber. Due to the above phenomenon, the resonator cannot generate a sound of a target resonance frequency in the apparatuses of the Patent Literatures 1, 2. Thus, an actual resonance frequency deviates from a designed resonance frequency, and thereby a sufficient amount of reduction of the pulsation cannot be achieved.